The 'S&M' singer headed to exclusive London nightclub Boujis with her model pal and her entourage on Sunday night (16.06.13) after her 'Diamonds World Tour' show at Twickenham Stadium.

The 25-year-old pop star hit the club to support her younger brother GQ Gallest - whose real name is Rorrey Fenty - as he gave a rap performance, cheering him on from the sidelines.

A source said: ''She danced on the seats most of the night with Cara. Rihanna cheered the loudest for her brother when he performed, he seemed a bit nervous at first but soon felt relaxed when his sister arrived.''

The superstar and her party - which also included her best friend Melissa Forde - sipped on expensive bottles of Ciroc coconut vodka, champagne and Hennessy cognac, and they stayed at the venue until closing time.

Aside from cheering her own brother, Rihanna was also spotted belting out the lyrics to songs including Rudimental's 'Waiting All Night Long' and her own chart-topping hit 'Diamonds'.

Her sidekick Cara appeared ''a little worse for wear'' by the end of the night and was spotted sporting a lanyard printed with her name, photo and the word 'friend' to show why she should have been backstage at Rihanna's stadium show earlier.